If you read the current SESAR documentation, you cannot fail to notice one of the more serious misunderstandings that still prevail in the project. In SESAR terminology, ATM progress goes from time-based operations to trajectory based operations (TBO) and then to performance based operations. This reveals the, oft bemoaned, confusion between TBO and performance based operations. Under PBO we will still be using the TBO paradigm… But never mind, that will be the subject of another article.
This time round I would like to introduce to you a new development, a true time-based operations gem that goes under the name SARA (Speed and Route Advisor) and which will be implemented in the Amsterdam FIR starting in 2012 with the functionality expanding stepwise in the following period.
So what is SARA and what does it do?
One of the big capacity guzzler in busy TMAs is the unpredictability and instability of the arriving stream of aircraft. The numerous conflicts require constant radar vectors and radio traffic, resulting in high workload for both pilots and controllers as well as often inefficient trajectories. Developing an effective arrival management system is a real challenge.
The objective of SARA is to give advice on speed and/or routing to (Upper) Area Controllers in order to achieve the planned arrival time(s) of the aircraft over fixes (and implicitly via the Inbound Planning (IBP) function over the runway threshold).
A system like this must plan and control arriving traffic in such a way that the flights form a smooth and reliable stream of traffic. The result is improved flight efficiency due to improved flight profiles and lower workload both in the air and on the ground. Reduction of the environmental impact is an important benefit, of particular significance at an airport like Schiphol.
In line with the initial improvements planned in SESAR, SARA will contribute to a more accurate delivery of traffic at the Initial Approach Fix (IAF) and reduce the workload of the controllers working with SARA in the CTAs. The accurate delivery of traffic at the IAF will in turn reduce the workload of the controllers working in the TMA. SARA will reduce the number of tactical clearances (and thus the R/T load), because of its ability to generate a single, comprehensive, solution for meeting the time at the IAF. At a later stage SARA could progress to providing conflict free solutions. The findings in similar projects, like the En-route Descent Advisor (EDA) developed by NASA confirm the validity of these benefits.
The concept was validated in a series of simulations and live trial exercises at Schiphol airport in 2009. The trial involved some 260 flights, the overwhelming majority of which hit the target time with a +/- 30 second margin which was right on the dot for the exercise. These trials, which were part of Boeing’s global program to promote Tailored Arrivals, convinced controllers that it was the right direction to go in order to achieve a more predictable and stable operation.
As such, SARA will be an important element in the ATM system supporting the SESAR Concept of Operations calling for a more stable and predictable ATM environment.
Amsterdam is not forgetting that a tool like SARA can only work well if all ATC units feeding its traffic are also involved. In due time implementation will be coordinated with adjacent centers Maastricht UAC and UK air traffic services provider NATS. Pre-streaming of inbound traffic to meet an accurate TMA entry time is one of the key goals of the SARA implementation project.
SARA was developed in a partnership between KLM, Martinair, Transavia, Air Traffic Control The Netherlands, EUROCONTROL’s Maastricht UAC, NLR and Boeing.
In the current implementation phase KLM, Air Traffic Control The Netherlands, EUROCONTROL’s Maastricht UAC, and NLR are involved.
A PowerPoint presentation on SARA is available here.
Information about SARA is also available on the Mainport Schiphol Knowledge & Development Centre website.
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